Correct approach to logging via interception / injection

We have been discussing adding some instrumentation / logging code to one of our applications and as part of that discussion we have raised the possibility of using some form of interception or injection
to avoid a cut and paste exercise throughout the code base etc....

We currently use Ent Lib but not PIAB or Unity, but given we use the other blocks it doesn't feel like a huge leap to consider these for managing the logging code. The question to me is which
approach should we go with, PIAB, Unity or a mix of the two?

The PIAB article on MSDN refers you to Unity as an alternative approach to implementing this feature, does that imply that Unity is the implementation of choice from a P&P perspective and that PIAB
may be deprecated some time in the future?

If not, is there any guidance as to which approach we should consider and when?

Additionally, are there any useful articles on how to do this with Unity, I got the PIAB example, but I must admit I got somewhat twisted trying to get my head round the Unity approach...